// Retrieves a Person object.
private static Person Retrieve(DbDataAccess dbDataAccess
  , DbColumns dataDefinition)
{
  Person retValue = null;

  // Create the list of included columns.
  // This list should include the database assigned columns.
  List<string> columnList = new List<string>();
  foreach (DbColumn column in dataDefinition)
  {
    columnList.Add(column.ColumnName);
  }

  // Create a Data Columns object with the included data definitions
  // and values from the data record.
  var dataColumns = DbCommon.QueryColumns(columnList, dataDefinition);

  // Create Key Columns.
  var keyColumns = new DbColumns()
  {
    { "Name", (object)"TestName" }
  };
  dataDefinition.LJCSetExcludeKeyValue("PrincipleFlag");

  var queryKeyColumns = DbCommon.QueryKeys(keyColumns, dataDefinition);

  // Create a query with the retrieve columns.
  // The retrieved columns should include the DB assigned columns.
  DbRequest dbRequest = new DbRequest()
  {
    Columns = dataColumns,
    KeyColumns = queryKeyColumns
    QueryType = QueryType.Select.ToString(),
    TableName = "PersonTest",
  };
  DbResult dbResult = dbDataAccess.Execute(dbRequest);

  if (dbResult != null)
  {
    string sqlStatement = dbResult.ExecutedSql;
    if (dbResult.DbRecords != null && dbResult.DbRecords.Count > 0)
    {
      retValue = new Person();
      DbCommon.SetObjectValues(dbResult.DbRecords[0], retValue);
    }
  }
  return retValue;
}